dt-bindings: remoteproc: Add Xilinx RPU subsystem bindings

Xilinx ZynqMP platform has dual-core ARM Cortex R5 Realtime Processing
Unit(RPU) subsystem. This patch adds dt-bindings for RPU subsystem
(cluster).

Signed-off-by: Tanmay Shah <[e-mail]>
Reviewed-by: Rob Herring <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Mathieu Poirier <[e-mail]>

Documentation/devicetree/bindings/remoteproc/xlnx,zynqmp-r5fss.yaml

···
+# SPDX-License-Identifier: (GPL-2.0-only or BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/remoteproc/xlnx,zynqmp-r5fss.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Xilinx R5F processor subsystem
+
+maintainers:
+  - Ben Levinsky <[e-mail]>
+  - Tanmay Shah <[e-mail]>
+
+description: |
+  The Xilinx platforms include a pair of Cortex-R5F processors (RPU) for
+  real-time processing based on the Cortex-R5F processor core from ARM.
+  The Cortex-R5F processor implements the Arm v7-R architecture and includes a
+  floating-point unit that implements the Arm VFPv3 instruction set.
+
+properties:
+  compatible:
+    const: xlnx,zynqmp-r5fss
+
+  xlnx,cluster-mode:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    enum: [0, 1, 2]
+    description: |
+      The RPU MPCore can operate in split mode (Dual-processor performance), Safety
+      lock-step mode(Both RPU cores execute the same code in lock-step,
+      clock-for-clock) or Single CPU mode (RPU core 0 is held in reset while
+      core 1 runs normally). The processor does not support dynamic configuration.
+      Switching between modes is only permitted immediately after a processor reset.
+      If set to  1 then lockstep mode and if 0 then split mode.
+      If set to  2 then single CPU mode. When not defined, default will be lockstep mode.
+      In summary,
+      0: split mode
+      1: lockstep mode (default)
+      2: single cpu mode
+
+patternProperties:
+  "^r5f-[a-f0-9]+$":
+    type: object
+    description: |
+      The RPU is located in the Low Power Domain of the Processor Subsystem.
+      Each processor includes separate L1 instruction and data caches and
+      tightly coupled memories (TCM). System memory is cacheable, but the TCM
+      memory space is non-cacheable.
+
+      Each RPU contains one 64KB memory and two 32KB memories that
+      are accessed via the TCM A and B port interfaces, for a total of 128KB
+      per processor. In lock-step mode, the processor has access to 256KB of
+      TCM memory.
+
+    properties:
+      compatible:
+        const: xlnx,zynqmp-r5f
+
+      power-domains:
+        maxItems: 1
+
+      mboxes:
+        minItems: 1
+        items:
+          - description: mailbox channel to send data to RPU
+          - description: mailbox channel to receive data from RPU
+
+      mbox-names:
+        minItems: 1
+        items:
+          - const: tx
+          - const: rx
+
+      sram:
+        $ref: /schemas/types.yaml#/definitions/phandle-array
+        minItems: 1
+        maxItems: 8
+        items:
+          maxItems: 1
+        description: |
+          phandles to one or more reserved on-chip SRAM regions. Other than TCM,
+          the RPU can execute instructions and access data from the OCM memory,
+          the main DDR memory, and other system memories.
+
+          The regions should be defined as child nodes of the respective SRAM
+          node, and should be defined as per the generic bindings in
+          Documentation/devicetree/bindings/sram/sram.yaml
+
+      memory-region:
+        description: |
+          List of phandles to the reserved memory regions associated with the
+          remoteproc device. This is variable and describes the memories shared with
+          the remote processor (e.g. remoteproc firmware and carveouts, rpmsg
+          vrings, ...). This reserved memory region will be allocated in DDR memory.
+        minItems: 1
+        maxItems: 8
+        items:
+          - description: region used for RPU firmware image section
+          - description: vdev buffer
+          - description: vring0
+          - description: vring1
+        additionalItems: true
+
+    required:
+      - compatible
+      - power-domains
+
+    unevaluatedProperties: false
+
+required:
+  - compatible
+
+additionalProperties: false
+
+examples:
+  - |
+    remoteproc {
+        compatible = "xlnx,zynqmp-r5fss";
+        xlnx,cluster-mode = <1>;
+
+        r5f-0 {
+            compatible = "xlnx,zynqmp-r5f";
+            power-domains = <&zynqmp_firmware 0x7>;
+            memory-region = <&rproc_0_fw_image>, <&rpu0vdev0buffer>, <&rpu0vdev0vring0>, <&rpu0vdev0vring1>;
+            mboxes = <&ipi_mailbox_rpu0 0>, <&ipi_mailbox_rpu0 1>;
+            mbox-names = "tx", "rx";
+        };
+
+        r5f-1 {
+            compatible = "xlnx,zynqmp-r5f";
+            power-domains = <&zynqmp_firmware 0x8>;
+            memory-region = <&rproc_1_fw_image>, <&rpu1vdev0buffer>, <&rpu1vdev0vring0>, <&rpu1vdev0vring1>;
+            mboxes = <&ipi_mailbox_rpu1 0>, <&ipi_mailbox_rpu1 1>;
+            mbox-names = "tx", "rx";
+        };
+    };
+...

include/dt-bindings/power/xlnx-zynqmp-power.h

···
 #ifndef _DT_BINDINGS_ZYNQMP_POWER_H
 #define _DT_BINDINGS_ZYNQMP_POWER_H
 
+#define		PD_RPU_0	7
+#define		PD_RPU_1	8
+#define		PD_R5_0_ATCM	15
+#define		PD_R5_0_BTCM	16
+#define		PD_R5_1_ATCM	17
+#define		PD_R5_1_BTCM	18
 #define		PD_USB_0	22
 #define		PD_USB_1	23
 #define		PD_TTC_0	24